Video: Fibrous Joint: Definition & Examples

In this lesson, you'll explore what a fibrous joint is, how it is classified, and what types of movement these joints allow. You'll also find how many forms of fibrous joints exist in the body and where they are located.

In this lesson, you'll explore what a fibrous joint is, how it is classified, and what types of movement these joints allow. You'll also find how many forms of fibrous joints exist in the body and where they are located.

What's a Joint?

Joints are any point in the body where one bone articulates, or meets, with another. It's an extremely general term that includes everything from the most obvious joints, such as those in your elbows and your knees, to the less obvious joints, like those between your teeth and the bone socket in which they sit. Since these joints all vary so much in structure, movement scientists decided to make things easier by creating two categories: the structural classification and the functional classification, which further clarify the differences between these joints.

The structural classification divides all of the joints of the body into three groups based upon the type of tissue that forms the articulation point. While fibrous joints are joined by fibrous connective tissue and cartilaginous joints are joined by cartilage, synovial joints have a cavity filled with synovial fluid that lubricates the adjacent bones.

The functional classification refers to the functional movement, or range of movement, of the joints. Synarthrotic joints are the most stable and, therefore, the least flexible; in other words, they are a synthesis, or unit, of bone. Amphiarthrotic joints have limited mobility. Just like amphibians who live both on firm land and in fluid water, these joints are 'amphi,' which means they are both stable and somewhat flexible. Lastly, diarthrotic joints are the most flexible joints; they have 'di' (two) directions of flexibility. These joints account for any highly movable articulations, such as your hips, wrists, and knuckles.

With that being said, it makes sense that synovial joints, or those having lubricating synovial fluid, are diarthrotic, which means having the greatest range of movement. Fibrous joints (those connected by fibrous tissue) are mostly synarthrotic, (the most inflexible).

Types and Locations of Fibrous Joints

There are three subtypes of fibrous joints that differ according to the length of the collagen fiber attachment:

Sutures are joints found only in the skull and are formed by interlocking bones joined by very short collagen fibers. In the fetal skull, the bones are widely spaced and connected by longer collagen fibers. In the process of birth, the fibers allow the bones of the skull some movement and pliability. After birth, these spaces, known as 'soft spots' of the head, will begin to fill with bone deposits and ossify into sutures.

Gomphosis are joints only found in the socket between the teeth and the maxilla (upper jaw) and the mandible (lower jaw). These bones have very short collagen fiber connections called periodontal ligaments that allow for only very slight movement. This slight movement provides cushioning between your teeth and jaws when you apply the 70 pounds per square inch of force that the human jaw is capable of during chewing.

Syndesmosis are joints formed by cords of ligament (fibrous, membranous sheets of connective tissue attaching to bone). They are found between the long bones of your forearm and connect your ulna to your radius, as well as in your shin between your tibia and fibula bones.

Lesson Summary

Fibrous joints are any place in the body where two or more bones are joined by a fibrous tissue connection known as collagen. They are mostly synarthrotic and have very little to absolutely no movement, which results in their extreme stability.

There are three types of fibrous joints:

Suture joints are interlocking articulations between the plates of your skull

Syndesmosis joints are ligament (membranous connections) points found between many long bones, such as the radius and ulna and the tibia and fibula

Gomphosis joints are found between the teeth and the sockets of the maxilla or mandible in which they sit

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